Static means generating content once (or rather on every change), rather than every time the content is requested.The speed and efficiency at scale can be up to 8 times faster and therefore 8 times cheaper. Nothing loads in a browser faster than a plain html file. Classic webapplications or CMS (like Wordpress, Joomla) generate the html every time they receive a request from a visitor. Once that happens they have to query the database and run through many code to generate the html for the browser. Depending on the used software, hardware and amount of requests this generating needs time which can amount to seconds. If there is massive increase in traffic and sites overload, this will cause them to slow down or even become unavailable temporarily (called slashdot effect). Most sites use web caching to avoid this.